Portable fluid mixer



Jan. 15, 1963 Filed May 22, 1959 G.G.STEVENSON PORTABLE FLUID MIXER 4Sheets-Sheet l Jan. 15, 1963 G. G. sTEvENsoN 3,073,577 PORTABLE FLUIDMIXER Filed May 22. 1959 4 Sheets-Sheet 2 E Aard/11,47% oFF 00W/V y XJan. 15, 1963 G. G. sTEvENsoN 3,073,577

PORTABLE FLUID MIXER Filed May 22, 1959 4 Sheets-Sheet 3 Jan. 15, 1963G. G. sTEvENsoN 3,073,577

PORTABLE FLUID MIXER Filed May 22, 1959 4 Sheets-Sheet 4 United StatesPatent This invention relates to an apparatus for mixing huid materialssuch as uid materials including a catalyst to produce a highly viscosesealant composition of the general character of a synthetic rubber-likesealant known f to the trade as Thiokol. An apparatus of this type isdisclosed in the Trumbull et al. Patent No. 2,859,017, which disclosureis hereby incorporated in the present disclosure by reference.

In a typical use for such a composition, the sealant mixture is placedin dispensing tubes having suitable dispensing nozzles by means of whichthe sealant is applied where required. Once such a mixture is compoundedwith the included catalyst, it must be used within a few hours. For thisreason, the sealant is mixed in small batches only as required.

The invention is particularly directed to the problems involved inproviding such an apparatus in the form of a portable unit that may beused on construction jobs.' 'The invention thus meets a need for acompact light-weight unit which may be used in a time-saving manner tomix `sealant for application to a building structure, for example, toform seals around metal window frames.

One of the problems involved is to keep the weight of the apparatus low.This problem is met by a light-weight upright structure which consistsessentially of a lightweight horizontal base and a hollow upright columnxedly mounted on the base structure. structure with all the workingparts mounted thereon may be easily lifted from a truck by one man andplaced on the ground 'or on any avail-able surface ready for operation.

A feature of the invention is the manner in which it provides for mixingthe ingredients in the original container in which the ingredients aresold.` The unit provides a can opener to remove the top of the usualcylindrical metal container and the unit provides a closure which isslidingly mounted inside the container to replace the removed top. Theunit further provides a dasher inside the container beneath the Aclosurefor reciprocation to mix the ingredients with the required efliciency.

One of the problems to which the invention is directed is to cause theclosure to coniine the ingredients in the Such a support container in anairtight manner and to permit power to be transmitted through theclosure to actuate the dasher for cyclic movement between the closureand the bottom of the container.y For this purpose, the inventionprovides spring means to urge the closure downward against the confinedingredients with the required force and further positions the dasher onthe lower end of' a shaft that extends slidingly through the closure.

A motor for driving the shaft is mounted on the upright column in avertically movable manner and the motor driven shaft is formed with ascrew thread that is engaged by a fixed threaded collar. of the shaft bythe motor causes the shaft to shift axially by screw action, the motorshifting with the shaft. The dasher at the lower end of the shaft movesaxially with the shaft and simultaneously rotates with the shaft. The

pensing the completely mixed ingredients. For this purpose, the closureis provided with a dispensing port or nozzle for filling dispensingtubes and provision is made for operatively connecting the closure tothe vertical shaft in such manner that the closure may be drivendownward by the motor to dispense the mixed materials. In accord withthis concept, a control arrangement i-s provided which permits the motoreither to operate automatically for the mixing operation or to Aoperateunder close manual control for the dispensing operation.

The rnotor may be either an electric motor or an air motor. In manyinstances where compressed air is available on a construction job, it ismore convenient to use compressed lair for the motive force instead ofelectricity. In this regard, a feature of the invention is the provisionof pneumatic controls for a pneumatic motor which permits the pneumaticmotor, like the electric motor, 'to be either reciprocated automaticallyfor the mixing operation or to be manually controlled for actuating theclosure in the dispensing operation.

'The various features and advantages of the linvention may be understoodby reference to the following detailed description and the accompanyingdrawings.

In the drawings, which are to be regarded as merely illustrative:

FIG. l is a side elevation with parts broken away showing the presentlypreferred embodiment of the invention which incorporates an electricmotor;

FIG. la i-s a somewhat enlarged fragmentary View, partly in sideelevation and partly in section, showing how a split thrust collar maybe mounted on the vertical shaft to force the closure member downward;

FIG, 2 is a sectional view taken as indicated by the line 2--2 of FIG.l; ,Y

FIG. 3 is a side elevation of the same apparatus as seen along the line3 3 of FIG. l;

FIG. 4 is a fragmentary view partly in side elevation and partly insection illustrating the dispensing operation; j A

FIG. 5 is lan enlarged bottom plan View of the dasher;

FIG. 6 is a wiring diagram of the control system;

FIG. 7 is a diagram of an air motor and an associated control system;

FIG. 8 is a diagram of the valve arrangement in the valve block in FIG.7; i

FIG. 9 is a sectional view showing the construction of one of the valvesin the valve block; and

FIG. l0 is a view partly in side elevation and partly in section showinghow the reversing valve unit of FIG. 7 may be constructed.

General Arrangement The essential parts of the first embodiment of Vtheinvention shown in FIGS. 1 to 5 include: an upright support structurecomprising a base 2t) and a hollow column 22 of rectangular crosssection; a jacket 24 to removably embrace and reinforce an open-toppedcontainer 25 on Thus the rotation motor is reversible and means isprovided to reverse the 'l the base 20; a closure member 26 with acircumferential O-ring 27 to tit slidingly in the container 25 againstthe ingredients therein; a slide member 28 that is slidingly mounted onthe rectangular column 22 and carries the closure member 26; a coilspring 29 inside the hollow column 22 to urge the slide member 28downward thereby to urge the closure member 26 downwardly against theingredient-s in the container 25; a pivoted latch arm 30 to releasablyengage the slide member 28 to hold the closure member 26 elevated inopposition tothe coil spring 29 for cleaning operations; a dispensingnozzle y317m the closure member 26 which nozzle may be closed whendesired by an elongated plug 32; an electric motor 34 that is slidablymounted on the hollow column 22 for vertical movement; a motor shaft 35extending downward from the motor through the closure member 26, whichshaft has a screw thread 36 above the closure member; a fixed sleeve 38that is supported by the column 22 and is internally threaded forengagement with the screw thread 36 of the motor shaft to cause theshaft and the motor to move vertically by screw action in response torotation of the shaft; a split thrust collar 39 (FIG. la) that may beremovably mounted on the motor shaft 35 for abutment against the closuremember 26; a dasher 4t) with a circumferential series of elongatedapertures 41 (FIG. 5), the dasher being fixedly mounted on the lower endof the shaft 35 below the closure member 26 to be rotated by the shaftand to be simultaneously reciprocated between the bottom of thecontainer and the closure member for the purpose of intermixing theingredients in the container; a reversing switch 42 movable with themotor 34 for reversing the motor; an upper stop 44 connected with theclosure member 26 for contacting the reversing switch 42 to reverse themotor when the dasher approaches the closure member; a second fixedlower stop 45 to contact the reversing switch for reversing the motorwhen the dasher approaches the bottom of the container 25 a manuallyoperable master switch 46 to start and stop the motor 34; a manuallyoperable three-position switch 48 having an up position, a stop positionand a down position for manual control of the motor 34; and a selectorswitch 50 movable to one position to place the motor under the controlof the reversing switch 42 and movable to an alternate position to placethe motor under the control of the manual switch 48.

This embodiment of the invention further includes a can opener 52 forthe convenience of the operator, the can opener being mounted on therectangular column 22 by means of a bracket arm 54. This can opener maybe of conventional construction.

Operation The sealant material is supplied in the closed container withthe necessary catalyst in a separate receptacle. The can opener 52 isemployed to remove the top of the container in a smooth manner and thecatalyst is then introduced into the sealant material in the container.With the motor shaft 35 at an upper position and the dasher 40 on thelower end of the shaft holding the closure member 26 at anelevatedposition, the open-top container 25 is placed on the base 20 andenclosed by the jacket 24. r[he split thrust collar 39 is then placed onthe motor shaft 35 above the closure member 26 thereby operativelyconnecting the closure member to the motor shaft for downward movementtherewith. The three-position manual switch 48 is placed in its neutralposition; the selector switch 50 -is positioned for manual operation;and the master switch 46 is closed in preparation for manual operation.

The three-position manual switch 48 is then manipulated to cause themotor shaft 35 to move downward by screw action with the thrust collar39 abutting the closure member 26 to force the closure member downwardinto the open-topped container 2S; The dasher 40 is close to theunderside of the closure member 26 when the thrust collar 39 is used.The three-position manual switch 48 is jogged during this operation,i.e., repeatedly shifted between its stop and down positions to lowerthe closure member 26 cautiously and to give opportunity for theopen-top container to be manuevered into an accurately centered positionfor receiving the closure member. Cautious downward movement of theclosure member 26 is continued to lower the closure member against thematerial in the open-top container and to give the free air on top ofthe material a chance to escape through the nozzle 31. When the materialstarts to flow out of the nozzle, the plug 32 is screwed into thenozzle.

The split thrust collar 39 is then removed from the motor shaft 35 andthe selector switch 50 is positioned to place the motor under control ofthe reversing switch 4 2 for automatic operation. The motor rotates theshaft 35 to reciprocate the dasher 40 with the reversing switch operatedby the upper stop 44 when the dasher approaches the closure 26 and withthe reversing switch operated by the lower stop 45 when the dasherapproaches the bottom of the container 25. Each downward movement of theshaft 35 displaces material in the container to cause correspondingupward movement of the closure member 26 against the resistance of thespring 29.

The dasher 40 is highly effective because the central area, i.e., thearea of the inner half of the radial dimension, is blank so thatmaterial in the path of the dasher is displaced radially outward to thedasher slots 41. With the dasher rotating as well as reciprocating, theinclined slots 41 are especially effective for intermixing theingredients.

When the dasher 40 has been reciprocated through the number of cyclesfor complete and homogeneous inter` mixture of the ingredients in thecontainer 25, the motor is stopped either by means of the master switch46 or by placing the three-position manual switch 48 in its stopposition. The selectorswitch 50 is then moved to the position for manualoperation. With the selector switch 50 positioned for manual operation,with the three-posi tion manual switch 48 at its stop position, and withthe master switch 46 closed, the three-position switch 48 is joggedupward to shift the motor shaft 35 upward cautiously to a position withthe dasher 40 close to the closure member 26 to permit the thrust collar39 to be again installed on the motor shaft 35. The plug 32 is thenremoved to open the nozzle 31 so that cartridges may be filled for usein applying the sealant for its purpose.

FIG. 4 shows how a cartridge 55 may be positioned by hand against thenozzle 31 for a lling operation. To ll the cartridge, the three-positionmanual switch 48 is jogged downward for cautious downward movement ofthe closure member 26 to force the mixed material out of the containerthrough the nozzle 31 into the cartridge. When the cartridge is full,the three-position manual switch 48 is jogged upward slightly to relievethe pressure sufficiently to keep the mixed material from gushing out ofthe nozzle 31 when the filled cartridge is removed.

The dasher 40 may be removed from the shaft 35 for cleaning whendesired. For this purpose the motor is operated to lift the slide member28 and then the latch arm 30 is placed under the slide member to holdthe closure member 26 elevated against the pressure of the spring 29.The dasher 40 may then be removed from the lower end of the shaft.

Structural Details The jacket 24 that serves to embrace and reinforce anopen-top container 25 is of split construction wtih separable ends andis provided with a pair of latches 62 to hold the two ends in closedposition. The jacket 24 has lugs 64 to receive the thrust of downwardlyinclined thumb screws 65 on opposite sides of the jacket, the thumbscrews extending through brackets 66. Once a jacketed can is centered inaxial alignment with the motor shaft 35 by the introduction of theclosure member 26 into the upper open end of the container, the thumbscrews 65 may be tightened to immobilize the container and to resist thetendency of the container to be lifted by upward movement of the dasher40.

The hollow column 22 is reinforced by a brace member 68 that extendsdiagonally upward from the base 20. The previously mentioned latch arm3G is mounted on the Vbase 20 by a hinge 70 and a suitable tensionspring 72 connects the latch arm with the brace member 63 to urge thelatch arm to its release position that is shown in solid lines in FIG.l.

The motor shaft 35 has a smooth lower end portion 74 which slidesthrough the closure member 26 in a fluid-tight manner and, as shown inFIG. la, has a neck portion 75 at the lower end of the screw thread 36to receive the previously mentioned split thrust collar 39. The thrustcollar 39 is made in two halves which may be reasonably connected by apair of screws 76. The closure member 26 has an upwardly extendingtubular portion 78 which slidingly embraces the smooth lower end portion74 of the shaft 35 for guidance thereby. The tubular portion 78 isinternally enlarged as indicated at 80 throughout the major portion ofits length to clear the screw thread 36.

The closure member 26 is integrally connected with the slide member 28by an arm 82 and the slide member is provided with a cross-pin 84 thatextends through a pair of diametrically opposite longitudinal slots 85in the rectangular column 22. Inside the hollow column 22, the crosspin'84 extends through a block 86 at the lower end of an upright rod 88.The upright rod 88 slidingly extends through a cap 90 at the upper endof the hollow column 22 to follow the vertical movements of the slidemember 28 and the closure member 26. The previously mentioned coilspring 29 that urges the closure member 26 downward surrounds theupright rod 88 in compression between the lower block 86 and the uppercap 90x Thus, the spring 29 continuously urges the closure member 26downward.

Mounted on the upper end of the upright rod 88 is an angular bracket 92that carries the upper stop 44 for the reversing switch 42, this upperstop being in form of an adjustable screw with a lock nut 95. Since theupper stop 44 carried by the upright rod 88 is fixed relative to theclosure member 26 and since the reversing switch 42 travels with thedasher 40, the upper stop operates the reversing switch to reverse themotor 34 whenever the `dasher 40 approaches the closure member. A secondlower stop 45 for the reversing switch comprises an adjustable screwprovided with a lock nut 98, thel screw being threaded into a flange 100of the previously mentioned bracket arm 54.

The motor 34 together with a switch box 102 and a resistor box 104 forthe motor are carried by an upper slide member 105 that slindinglyembraces the hollow column 22. The switch box 102 carries the previouslylmentioned master switch 46, the three-position switch 48, the selectorswitch 50 and the reversing switch 42.

The reversing switch 42 is of the toggle type with an operating arm 106.Slidingly mounted in the switch box 162 and extending upward therefromis an upper operating plunger 108 for the reversing switch 42 which isnormally held at an upper limit position by a coil spring 110. Thisoperating plunger is in the path of the upper stop member 44 so thatupward movement of the slide member 185 eventually causes retraction ofthe upper operating plunger by the upper stop member 44 to cause theoperating plunger to swing the operating arm 106 of the reversing switchdownward to reverse the motor 34. In like manner, a lower operating-plunger 112 is slidingly mounted in the switch bov 102 and extendsdownward therefrom for contact with the lower stop member 45, theplunger being normally held at its downward limit position by asurrounding coil spring 114.

Certain safety provisions have been found to be desirable to preventdamage to the structure by movement of the motor too far upward duringmanual operation and by movement downward against the latch member 30when the latch member is holding the closure member 26 up. Damage byexcessive upward movement of the motor 34 is avoided by providing asuitable limit switch to be effective whenever the selector switch 50 ispositioned for manual operation. For this purpose, a limit switch 115may be mounted on the motor 34 for movement against a stop 116 that isxedly mounted by a bracket 11S on the upper end ot the hollow column 22.This limit switch automatically reverses the motor when- 6 ever themotor is moved too far upward by manipulation of the three-positionedmanual switch 48.

Damage that might be caused by forcing the closure 26 downward when thelatch arm 30 is in its latching' position is avoided by employing alatch block 120 on the latch arm 30 to engage the lower edge ofthe'slide member 28. The latch block 120 is secured to the latch arm 30by suitable frangible means which will break when stressed unduly. Forthis purpose, the latch block 120 may be attached to the latch arm byrelatively weak frangible rivets 122. The upper end of the latch arm 30is bent backwards to an angle as indicated at 124 to make the latch armineffective in the absence of the latch block 120. Thus with the latchblock 120 removed, the operator cannot employ the latch arm for itspurpose without replacing the latch block by .a new set of trangiblerivets.

As a further safeguard, the latch arm 30 is made short enough in lengthto hold the closure member 26 at a position too low to permit thecontainer 25 to be positioned under the closure member. With the closuremember held elevated against the resistance of the spring 29 by thelatch arm 30, the operator nds it necessary to jog the three-positionmanual switch 48 upward to lift the `closure to provide clearance forthe container 25. The upward movement of the closure member permits thelatch arm to be automatically retracted by the spring 72.

Wiring Diagram FIG. 6 shows a diagram of an electrical control systemthat may be employed in the described embodiment of the invention. Thepreviously mentioned motor 34 has a pair of field coils by means ofwhich the direction of rotation of the motor may be reversed. Theselector switch 50 is a double-throw double-pole switch, the blades ofwhich are connected to the armature of the motor 34. The three-positionmanual switch 48, the reversing switch 42 and the upper limit switch 115are also of the doublepole double-throw type. One pair of contacts 126of the selector switch 50 that are employed for manual operation of thedasher 40 are connected to the switch blades of the three-positionswitch 48, as shown, and the second pair of contacts 128 of the selectorswitch 50 that are used for automatic operation are connected to theswitch blades of the reversing switch 42.

The pair of contacts 130 of the reversing switch 42 that are used toenergize the motor 34 for downward movement of the motor shaft 35 areconnected to the two eld coils 125 respectively and are connected to theblades of the limit switch 115. The pair of contacts 130 are alsoconnected to the corresponding pair of contacts 132 of thethree-position selector switch48 that are employed for downward movementof the motor shaft. The second pair of contacts 134 of the reversingswitch 42 that are employed for upward movement of the motor areconnected to the corresponding pair of contacts 135 of thethree-position manual switch 48 and the pair of contacts 135 areconnected, in turn, to a pair of contacts 136 of the limit switch 115.

The blades of the three-position manual switch 48are connected to thesecond pair of contacts 137 of the upper limit switch 115. One of theeld coils 125 of the motor is in series with the master switch 46 andwith a pair of motor resistors 138 that are housed in the previouslymentioned resistor box 104. The purpose of these resistors is to lowerthe voltage drop across this particular motor to permit the motor to bereversed in the manner described.

The limit switch 115 functions actually as a reversing switch to keepthe motor from coasting past the desired limit position. If thethreeposition manual switch 48 is held -in its up position after theupper limit switch V115 is operated, the motor will be continuallyreversed tion, however, will inform the operator that the threepositionmanual switch 48 should be shifted to its stop position.

Operation by an Air Motor As heretofore stated, in some instances, it isdesirable to substitute an air motor for the electric motor 34 sincecompressed air is commonly available on construction jobs. FIGS. 7 to 9show diagrammatically how the above described apparatus may be modifiedby the substitution of an air motor 140 for the electric motor, the airmotor functioning to operate a motor shaft 35a which corresponds to thepreviously mentioned motor shaft 35. The air motor 140 may be connectedto a suitable source of compressed air through a conduit 142 which isequipped with a master start and stop valve 144 and which leads to avalve block 145.

As indicated diagrammatically in FIG. 8, the supply conduit 142 isconnected to two branch passages 146 and 148 inside the valve block 145and these two passages are connected to the air motor 140 bycorresponding pipes 150 and 152. The flow of pressurized air through thebranch passage 146 is controlled by a valve 154 which is apilot-operated valve having a pilot tube 155. In like manner, ow throughthe second branch passage 148 is controlled by a similar valve 156having a pilot tube 158.

An exhaust pipe 160 which is connected with the branch passage 146between the air motor and the valve 154 is controlled by an exhaustvalve 162 having a pilot tube 164. In like manner, an exhaust pipe 165that is connected to the second branch passage 148 is controlled by anexhaust valve 166 having an associated pilot tube 168.

The manner in which each of the four valves 154, 156, 162 and 166operate may be understood by reference to the diagrammatic view in FIG.9 which -represents the valve 154 in the branch passage 146. In FIG. 9,a valve body 170 has an inlet passage 172 which terminates at a valveseat 174 in a valve chamber 175. The valve seat is normally closed by avalve member 176 which is unitary with a piston 178 that is slidinglymounted in the valve chamber and is provided with an O-ring 180. Asuitable coil spring 182 in compression between the piston 178 and theend of the valve chamber at the valve seat 174 exerts pressure on thepiston in a direction to unseat the valve member 176. An outlet passage184 for the actuating air is connected to the valve chamber 175 toreceive air from the inlet passage 172 when the valve member 176 isunseated. The pilot tube 155 for the valve 154 s connected to the branchpassage 146 on the inlet side of the valve and also communicates withthe valve chamber 175 through a bore 185.

If the outer end of the pilot tube 155 is closed, the pressure in thevalve chamber 175 above the piston 178 will be the relatively highpressure that exists in the branch pipe 146 on the inlet side of thevalve. If the valve member 176 is seated while the outer end of thepilot tube 155 is closed, it will remain seated against the same uidpressure in the inlet passage 172 because the piston 178 is sutlicientlylarger than the nose of thevalve member 176 to keep the valve memberseated in opposition to the opening force exerted by the spring 182. Ifthe outer end of the pilot tube 155 is opened to the atmosphere,however, the pressure drops in the valve chamber 175 above the piston178 to such an extent that the spring 182' lifts the valve member 176off its seat to permit air flow through the valve. If the outer end ofthe pilot tube 155 is suddenly closed while the valve member 17 6 isunseated as shown in FIG. 9, the pressure in the valve chamber 175 abovethe piston 178 again rises to the line pressure in the branch pipe 146and the valve closes. Thus the valve shown in FIG. 9 cuts off flow ofcompressed air whenever the pilot tube 155 is cut otf from theatmosphere and opens whenever the pilot tube is vented to theatmosphere.

The pilot tube 155 of the valve 154 and the pilot tube 168 of the valve166 are both connected to a control tube 186 so that the two valves openwhenever the control tube 186 is vented to the atmosphere and closewhenever the control tube 186 is cut oi from the atmosphere. In likemanner, the pilot tube 158 of the valve 156 and the pilot tube 164 ofthe valve 162 are connected to a second control tube 188 to openwhenever the control tube is vented to the atmosphere.

It is apparent from an inspeciton of FIG. 8 that with the control tube188 cut cfrr from the atmosphere and the control tube 186 vented to theatmosphere, the valves 156 and 162 will be closed and the valves 154 and166 will be open. With the valve 154 open, air under pressure issupplied to the air motor through the branch pipe and air from thedischarge side of the motor is exhausted through the exhaust valve 166.

On the other hand, with the control tube 186 cut off from the atmosphereand the control tube 188 vented to the atmosphere, the valves 154 and166 will be closed and the valves 156 and 162 will be open. With thevalve 156 open, compressed air is fed to the motor through the pipe 152and the exhaust `from the motor is released to the atmosphere throughthe valve 162. Thus alternately opening the control tubes 186 and 188 tothe atmosphere will cause the air motor 140 to rotate alternately inopposite directions.

The two control tubes 186 and 188 are connected to two normally closedvalves 190 and 192 respectively, which two valves together correspond tothe three-position manual switch 48 in the previously described controlcircuit. Thus if the two valves 190 and 192 are closed, the air motor140 will be idle; if solely the valve 190 is opened, the motor willrotate in a direction to cause the motor shaft 35a to shift upward; andif solely the valve 192 is opened, the air motor will rotate in thereverse direction to cause the shaft 35a to shift downward. These twovalves 190 and 192 are preferably of the push button type, both beingoperated by corresponding plungers.

The control tube 186 is connected by a branch tube 194 to a valve 195and the control tube 188 is connected by a branch tube 196 to a secondvalve 198. These two valves 195 and 198 are mechanically interconnectedfor operation in unison by a selector lever 200. In the position of theselector lever 200 shown in FIG. 7, the two valves 195 andV 198 areclosed so that control of the air motor 140 resides solely in the twovalves 190 and 192. In the alternate position of the selector lever 200,the valve 195 places the branch tube 194 in communication with a controltube 202 that leads to an automatic reversing valve unit that isgenerally designated by numeral 204. At the same time, the valve 198places the branch tube 196 in communication with a control tube 205 thatalso leads to the reversing valve unit.

The reversing valve unit 204 is shown diagrammatically in FIG. 7 ashaving a control arm 206 by means of which it may be operated in thesame manner as a toggle type reversing switch. Thus when the control arm206 is inclined downward as shown in FIG. 7, the control tube 205 isvented to the atmosphere to cause the air motor 140 to operate in adirection to shift the motor shaft 35a downward. On the other hand, whenthe control arm 206 is inclined upward, the control tube 202 is open tothe atmosphere to cause reverse rotation of the air motor 140.

The automatic reversing valve unit 204 travels up and down with the airmotor 140 and the shaft 35a. An upwardly extending rod 210 and adownwardly extending rod 212 also travel with the motor and shaft. Therod 210 is urged upward by a spring 214 and the rod 212 is urgeddownward by a spring 215 in the manner heretofore described. Theupwardly extending rod 214 moves against an upper stop 216 to reversethe air motor when the dasher approaches the closure member and thedownwardly extending rod 212 moves against a lower stop 218 to reversethe motor when the dasher approaches the botfom of the mixing container.

The air motor I140 may be stopped or started at any time by means of themaster valve 144. With the master valve 144 open to supply compressedair to the valve block 145 and with the selector arm 200 in itsn'ghtward position shown in FIG. 7, the motor may be moved upward ordownward selectively by manual operation of the two valves 190 and 192.With the selector lever 200 swung to its alternate limit position, themotor will operate and will automatically reverse under control of theautomatic reversing valve unit 204. It is apparent that the selectorlever 200 corresponds to the selector switch 50 of the previouslydescribed electric control.

The reversing valve unit 204 may be of the construction shown in FIG.10. In FIG. 10, the reversing valve unit comprises a pilot valve 220'having an operating plunger 222, the pilot valve being connected to thecontrol tube 205 and being spring-biased to take anopen position. If theoperating plunger 222 is not depressed, the valve takes an open positionto cause the air motor to operate to shift the shaft in the downdirection. In like manner, a lsecond pilot Valve 224 having an operatingplunger 225 is spring-biased to take an open position and is connectedto the control tube 202. If the operating plunger 225 is not depressedthe valve causes rotation of the motor for upward movement of the motorshaft.

The previously mentioned control arm 206 of the reversing valve unit 204is mounted on a pivot 226 and is integral with an upwardly extendingoperating arm 228 and a downwardly extending operating arm 230. Theupwardly extending operating arm 228 is positioned to depress theoperating plunger 222 and the lower operating arm 230 is positioned todepress the lower operating plunger 225. The upper operating arm 228 hasa latch finger 232 which overhangs a leaf spring 234 that is bent tofonn a latch shoulder 235. In like manner, the lower operating arm 230is formed with a latch linger 236 which overhangs a leaf spring 238 thatis bent to form a latch shoulder 240.

The previously mentioned upwardly extending operating rod 210 thatcooperates with the upper stop 216 is provided with a head 242 at isupper end which is slidingly encased by a tube 244. Below the head 242,the tube 244 is swaged to form an inner circumferential rib 245 and awasher 246 that loosely surrounds the rod 210 is urged against this ribby the previously mentioned spring 214. The rod 210 is rigidly connectedto the lower rod 212 through a central body 248 and this central body isopera-tively connected yto the control arm 206 by means of a stud 250which extends through a 4slightly oversized aperture 252 in the controlarm. The lower end of the rod 210 is surrounded by an upwardly extendingguide tube 254 that extends upward from the central body 248 and thelower end of the slidable tube 244 telescopes over this guide tube. Thepreviously mentioned spring 214 seats against the upper end of the guidetube 254.

The downwardly extending rod 212 is provided with a head 255 and isenclosed by a 'second slidable tube 256 with an inner circumferentialrib 258. The previously mentioned spring 215 is in compression between awasher 260 and the lower end of a guide tube 262.

'Ihe upper leaf spring 234 has an aperture 264 which surrounds the upperguide tube 254 to place the leaf spring in the path of downward movementof the slidable tube 244. In like manner, the lower leaf spring 238 hasan aperture 265 to surround the lower guide tube 262 in the path of theupward movement of the slidable tube 256.

With the parts of the reversing valve unit 204 in the positions shown inFIG. l0, the lower pilot valve 224 is free from mechanical pressure totake an open position and thereby open the control tube 202 to theatmosphere. On the other hand, the upper operating arm 228 depresses theoperating plunger 222 of the pilot valve 220 to cut oif the control tube205 from the atmosphere. Consequently, the reversing valve unit 204along with the air motor 140 is traveling upward to cause the upper endof 10 the upper slidable tube 244 to approach the upper stop 216. Underthese conditions, the upper latch linger 232 is in abutment with theupper latch shoulder 235.

When the slidable tube 244 makes contact with the upper stop 216 and thereversing valve unit continues its upward travel, the slidable tube isretracted downward against the opposition of the 'spring 214 and movesagainst the leaf spring 234 to flex the leaf spring sufciently todisengage the latch shoulder 235 from the latch linger 232. At thispoint, the two operating arms 228 and 230 t0- gether with the controlarm 206 are free for reversal movement, and the force of the compressedupper spring 214 swings the control arm 206 downward with a snap action.

The downward swing of the control arm 206 rocks the upper operating arm228 clockwise to release the operating plunger 222 of the upper pilotvalve 220 and also rocks the lower operating arm 230 clockwise todepress the operating plunger 225 of the lower pilot valve 224. Thelower latch finger 236 is swung past the latch shoulder 240 of the lowerleaf spring 238 and then the leaf spring exes to bring the latchingshoulder 240 into position to engage and retain the latch linger 236.Consequently, the control tube 202 is cut olf from the atmosphere andthe control tube 205 is vented to the atmosphere to cause downwardreversal of the air motor 140. When the reversing Valve unit 204approaches the lower stop 218, the reversing valve unit is operated inthe opposite respect to reverse the air motor for upward shift of theair motor shaft.

My description in 'speciiic detail of the selected practices of theinvention will suggest various changes, substitutions and otherdepartures from my disclosure within the spirit and scope of the'appended claims.

I claim:

1. In an apparatus for mixing ingredients in an opentop container, thecombination of: a closure for the open top of the container having avent for the release of air; yielding means to press said closuredownward against the ingredients in the container; an upright supportstructure; reversible power means movably mounted on said structure formovement longitudinally thereof; a shaft driven by said power means andextending downward therefrom through said closure, said shaft having ascrew thread above the closure; a dasher mounted on said shaft insidesaid container and beneath said closure; and fixed means engaging saidscrew thread to cause longitudinal movement of the shaft and power meansby screw action in response to rotation of the shaft whereby operationof said power means with periodic reversal causes said dasher toreciprocate axially of the container.

2. A combination as set forth in claim l in which said daslllier isixedly mounted on said shaft for rotation therewit 3. A combination asset forth in claim 1 in which said closure has an upwardly extendingcoaxial tubular portion slidingly embracing the shaft to maintain theclosure in axial alignment with the container.

4. A combination as set forth in claim l which includes latch means toreleasably hold said closure up to permit said dasher to be removed fromsaid shaft for cleaning.

5. A combination as set forth in claim 4 in which said latch means isautomatically releasable in response to upward movement of the closureaway from its latched position; and in which the latch means holds saidclosure at a height insuflicient to clear said container "whereby theclosure member must be moved upward from its latched position to lpermitthe container to be placed under the closure member.

6. A combination as set forth in claim 4 in which said latch means isfrangible to break in the event that said power means is inadvertentlyoperated against the resistance of the latch means. Y

7. A combination as set forth in claim l which in` Y 11 cludes means toreverse said power means in response to approach of the dasher to saidclosure and in response to approach of the dasher to the bottom of thecontainer.

8. A combination as set forth in claim 1, which includes means providinga port for dispensing the mixed ingredients from the container; andmeans to connect said closure to said shaft for axial movement therewithwhereby said power means may be employed to cause the closure to forcethe mixed ingredients out through said port.

9. A combination as set forth in claim 8 in which said dispensing portis in said closure.

10. In an apparatus for mixing ingredients in an opentop container, thecombination of: a closure for the open top of the container having avent for the release of air; yielding means to press said closuredownward against the ingredients in the container; an upright supportstructure; reversible power means movably mounted on said structure formovement longitudinally thereof; a shaft driven by said power means andextending downward therefrom through said closure, said shaft having ascrew thread above thel closure; a dasher mounted on said shaft insidesaid container and beneath said closure; and fixed means engaging saidscrew thread to cause longitudinal movement of the shaft and power meansby screw action in response to rotation of the shaft; means movable withthe power means and operable to reverse the power means; means in thepath of movement of said reversing means for contact therewith toreverse the power means when the dasher approaches the bottom of thecontainer; and means in the path of movement of said reversing means forcontact therewith to reverse the power means when the dasher approachesthe closure.

1l. A combination as set forth in claim 10 in which said last mentionedcontact means is fixed relative to said closure for movement therewithwhereby the range of reciprocation of the dasher is determined by thedistance between the closure and the bottom of the container.

12. A combination as set forth in claim 1l in which said power means isa motor and said reversing means is a reversing switch having anoperating member positioned for contact with said two contact means.

13. A combination as set forth in claim 11 in which said power means isa fluid motor and said reversing means comprises valve means having anoperating member positioned for contact with said two contact means.

14. In an apparatus for mixing ingredients in an opentop container, thecombination of: a closure for the open top of the container having avent for the release of air; yielding means to press said closuredownward against the ingredients in the container; an upright supportstructure; reversible power means movably mounted on said structure formovement longitudinally thereof; a shaft driven by said power means andextending downward therefrom through said closure, said shaft having ascrew thread above the closure; a dasher mounted on said shaft insidesaid container and beneath said closure; and fixed means engaging saidscrew thread to cause longitudinal movement of the shaft and power meansby screw action in response to rotation of the shaft; a first means forreversing said power means, said first means being movable with thepower means; means in the path of movement of said reversing means forcontact therewith to reverse the power means when the dasher approachesthe bottom of the container; means in the path of movement of saidreversing means for contact therewith to reverse the power means whenthe dasher approaches the closure; a second manually operable means forcontrolling the power means; a third means manually operable to connectsaid power means with said first and second means selectively; meansproviding a port for dispensing the mixed ingredients from thecontainer; and means to connect said closure with said shaft for axialmovement therewith to force the mixed ingredients out through said port.

12 15. A combination as set forth in claim 14 in which said power meansis an electric motor and said three means are switch means.

16. A combination as set forth in claim 14 in which lsaid power means isa fluid motor and said three means are valve means.

17. A combination as set forth in claim 16 in which said first meanscomprises: a pair of spring-loaded valves; a rocker member for operationby said two contact means to rock between a first limit position tooperate one of the valves of said pair in opposition to its springresistance and a second limit position to operate the other of thevalves of said pair in opposition to its spring resistance.

18. A combination as set forth in claim 16 in which said first meanscomprises: a pair of spring-loaded valves; a rocker member to rockbetween a first limit position to operate one of said valves inopposition to its spring resistance and a second limit position tooperate the other of said valves in opposition to its spring resistance;means to automatically latch said rocker member in response to movementthereof to its first limit position; means to automatically latch saidrocker member in response to movement thereof to its second limitposition; and oper ating means adjacent said rocker member; saidoperating means being movable in one respect by contact with one of saidcontact means to unlatch said rocker member at its first limit positionand to rock it to its second limit position with consequent latching ofthe rocker member at its second position and being movable in theopposite respect by contact with the other of said contact means tounlatch said rocker member at its second limit position and to rock itto its first limit position with conequent latching of the rocker memberat its first position.

19. In an apparatus for mixing ingredients in an opentop container, thecombination of: a base structure to support the container; uprightsupport structure mounted on said base structure adjacent the positionof the container; a closure to fit slidingly inside the open top of thecontainer; means connected with said closure and slidingly mounted onsaid upright support structure; spring means in stress between thesupport structure and said slidingly mounted means to urge said closuredownward against the ingredients in the container; motor means mountedon said upright support structure for vertical movement relativethereto; a shaft for rotation by said motor means and extending downwardthrough said closure; a dasher mounted on the lower end of said shaftbelow said closure for mixing the ingredients in the container, saidshaft having a screw threaded portion above the closure; means fixedlymounted on said upright support structure in engagement with said screwthread to cause longitudinal shift of the shaft and motor means by screwaction in response to rotation of the shaft by the motor means; andmeans to reverse the operation of said motor means in response toapproach of said dasher to the bottom of the container and in responseto approach of the dasher to said closure whereby the dasher isreciprocated to mix the ingredients in the container.

20A A combination as set forth in claim 19 which includes: meansproviding a port in said closure for dispensing the mixed ingredientsfrom said container; means to releasably connect said shaft to saidclosure with said dasher close to the closure whereby the closure may bemoved downward by the shaft to force the mixed ingredients out throughsaid dispensing port; means for manual control of said motor means forthe purpose of dispensing the mixed ingredients; and means to make saidmotor means responsive selectively to either said reversing means orsaid manual control.

21. A reversing valve assembly, comprising: a first valve operable in afirst direction and a second direction; a first spring constantlyexerting force on said first valve to operate the first valve in thefirst direction; a second valve operable in a first direction and asecond direction; a second spring constantly exerting force on saidsecond valve to operate the second valve in its rst direction; anoperating member to move in one direction to a first limit position tooperate said rst valve in its second direction in opposition to the rstspring and in the opposite direc-l tion to a second position to operatesaid second valve in its second direction in opposition to the secondspring; a rst latch means to latch said operating member at its rstlimit position in response to movement of the operating member thereto;a second latch means to latch said operating member at its second limitposition in response to movement of the operating member thereto; and acontrol member movable in one direction to release said first latchmeans and force said operating member from its rst limit position to itssecond limit position and movable in the opposite direction to releasesaid second latch means and force said operating member from its secondlimit position to its rst limit position.V

22. A combination as set forth in claim 21 in which portions of s aidoperating member and portions of said 14 two latch means are in the pathof movement'of said control member for contact by the control member.

vReferences Cited in the file of this patent UNITED STATES PATENTS787,191 Krewson Apr. 11, 1905 1,738,311 Oishei et al. Dec. 3, 19291,910,019 Kelly May 23, 1933 2,232,449 Habenicht Feb. 18, 1941 2,537,391Bakewell Jan, 9, 1951 2,831,606 Alters Apr. 22, 1958 2,859,017 Trumbullet al. Nov. 4, 1958 2,954,144 Elam et al. Sept. 27, 1960 FOREIGN PATENTS174,167 Austria Mar. 10, 1953 468,172 Germany Nov. 8, 1928

14. IN AN APPARATUS FOR MIXING INGREDIENTS IN AN OPENTOP CONTAINER, THECOMBINATION OF: A CLOSURE FOR THE OPEN TOP OF THE CONTAINER HAVING AVENT FOR THE RELEASE OF AIR; YIELDING MEANS TO PRESS SAID CLOSUREDOWNWARD AGAINST THE INGREDIENTS IN THE CONTAINER; AN UPRIGHT SUPPORTSTRUCTURE; REVERSIBLE POWER MEANS MOVABLY MOUNTED ON SAID STRUCTURE FORMOVEMENT LONGITUDINALLY THEREOF; A SHAFT DRIVEN BY SAID POWER MEANS ANDEXTENDING DOWNWARD THEREFROM THROUGH SAID CLOSURE, SAID SHAFT HAVING ASCREW THREAD ABOVE THE CLOSURE; A DASHER MOUNTED ON SAID SHAFT INSIDESAID CONTAINER AND BENEATH SAID CLOSURE; AND FIXED MEANS ENGAGING SAIDSCREW THREAD TO CAUSE LONGITUDINAL MOVEMENT OF THE SHAFT AND POWER MEANSBY SCREW ACTION IN RESPONSE TO ROTATION OF THE SHAFT; A FIRST MEANS FORREVERSING SAID POWER MEANS, SAID FIRST MEANS BEING MOVABLE WITH THEPOWER MEANS; MEANS IN THE PATH OF MOVEMENT OF SAID REVERSING MEANS FORCONTACT THEREWITH TO REVERSE THE POWER MEANS WHEN THE DASHER APPROACHESTHE BOTTOM OF THE CONTAINER; MEANS IN THE PATH OF MOVEMENT OF SAID